Cold weather advisory: Be Aware. A cold weather advisory is issued when seasonably cold air temperatures or wind chill values, but not extremely cold values, are expected or occurring. Be sure you and your loved ones dress appropriately and cover exposed skin when venturing outdoors.

The National Weather Service (NWS) had winter weather warnings in place for 11 states early on Thursday, with up to 1 foot of snow forecast for some parts of the country. Snow can disrupt travel and lead to hazardous driving conditions.

Rain and snow is returning to Oregon this weekend, and low elevation snow and ice will become possible next week.

On Saturday at 1:56 a.m. the National Weather Service issued a cold weather advisory valid from 10 p.m. until Sunday 10 a.m. for North Oregon Coast Range Lowlands, Central Oregon Coast Range Lowlands,

The long stretch of sunny and dry weather comes to an end on Thursday as clouds increase and Portland prepares for rain and potential snow.

"Light winds and limited air movement will lead to a period of stagnant air conditions," NWS said, warning of "deteriorating air quality for people with respiratory problems" and "visibility one quarter mile or less in dense fog," which "could make driving conditions hazardous."

But since then, things have dried out. National Weather Service meteorologist Chris Burling said Friday that overall, the Willamette Valley would continue to see cool and foggy weather for at least the next four to five days,

It should be another nice day today as our atmosphere gets set up for the winter weather pattern. Highs today will be in the 40s and 50s. We’ll have a mostly sunny start, but clouds will increase throughout the afternoon,

A surface inversion is preventing the normal mixing of air, meaning pollutants will remain trapped at lower altitudes.

The National Weather Service has simplified some of its winter weather alerts for Wind Chill and Extreme Cold Warnings.

Forecasters are warning that air pollution may become trapped and adversely affect humans, due to weather conditions in the U.S.

The National Weather Service is warning of air stagnation and dense fog in the Willamette Valley. Advisories have been issued for both events. Dense fog is expected to persist until 1 p.m ...